Helicopters have now become entrenched as an integral part of the weapons system carried by destroyers and frigates in anti-submarine search and strike capacity. Invariably, landings and take-offs of these helicopters from vessels must be made in moderate to severe turbulence and once on the deck, the helicopter must be quickly secured and stored for protection from the environment.
Such helicopters are the Sea Hawk (t.m.) and Sea King (t.m.).
The Sea King, a 20,000 pound helicopter, includes a conventional undercarriage comprising a rear wheel free wheeling through 360 degrees and a pair of spaced dual wheel units on either side, and near the nose of the helicopter. For recovery, employing the RAST System (Recovery Assist Secure and Traverse System) for helicopter recovery, the Sea King mounts externally on its underside an airborne messenger winch intermediate the rear wheel and a pair of dual wheel units. The messenger which holds a light duty cable with a messenger link and lock assembly for the flydown cable. When the flydown cable from the self-centering and self-balancing sliding bell mouth is secured to the messenger winch, a constant tension is maintained in the cable until the helicopter is landed safely. Once the helicopter has landed an increased tension is applied automatically by the electric tension winch for securing the helicopter.
After landing, the Sea King helicopter is moved into the hangar.
In Canadian Letters Patent No. 781,808 a helicopter rapid securing system is disclosed employing a constant tension winch used to maintain the tension in the cable securing the airborne helicopter to the ship and a frame surrounding the fairlead through which the cable extends below deck, supporting two parallel arresting rails for firing towards one another from opposite sides to the frame to capture the probe of the helicopter securing the cable to the helicopter when the helicopter has landed to secure the helicopter to the deck. Thereafter, the frame is withdrawn along the track traversing the Sea King helicopter to the hangar.
Of the known methods of securing and traversing a helicopter, the method described in Canadian Letters Patent No. 781,808 is the fastest and most reliable. It is also the most expensive. Additionally, because the capture and traverse functions are carried out by the same structure involved in helicopter haul-down, it is also safe. When the helicopter lands, not only is it secured to the ship's deck, it is also simultaneously secured to the traverser used for traversing it to the hangar. However, the said structure is complex and costly both to buy and maintain. Additionally, because the arresting beams are fired from opposite sides of the frame to engage the probe within the confines of the frame, the landing area is fixed in size.
U.S. Pat. No. 4,123,020 teaches an arm carrying a pair of digits arranged to move on a track by means of a right and left screw jack which is driven by a hydraulic motor. Each of the digits carries clamping jaws to secure the stud of the VTOL between the digits. This structure is not practical. Neither is the structure shown in U.S. Pat. No. 4,420,132. The scissors action of the arms may damage the probes.
U.S. Pat. No. 3,659,813 discloses the use of a trolley to which a helicopter is secured for traversing once on the deck of a ship. The trolley is displaceable along a worm gear mounted on the cross strut driven in a linear path by a drive mechanism. However, this system cannot be used to rapidly secure the helicopter on landing. It is merely a type of traversing device.
It is therefore an object of this invention to provide a helicopter rapid securing and traversing system and components and sub-assemblies therefor, which overcome the aforementioned difficulties with the prior systems and which are used to reliably and safely capture the probe of the helicopter time after time within a very short time (in the order of 1 to 2 seconds) without damaging the probe.
Further and other objects of the invention will be realized by those skilled in the art and from the following summary of the invention and detailed description of preferred embodiments thereof.